Study goal. To examine whether there are mental disorders in the immediate or extended families among youth in treatment. Study design. A cross-sectional study. Methods and participants. Analysis of the data from the medical history at the Department of Child and Adolescent Psychiatry, KBC Osijek for the period from 2010. to 2016. There were 457 respondents who answered questions inthe sociodemographic questionnaire. Results. The average age of the children participating in the study was 12.6 years, the minimum was two years and a maximum 22 years. The average age of the parents was 40.6 years. The mothers' average age was 38.9 years, and fathers' 42.3 years. The average number of children in families that participated in the study was 2.51. There were 113 (24.7%) families in which parents are divorced and 344 (75.3%) families where parents live together. Of 457 surveyed families, there were 262 (57.3%) families without diseases, while in 195 (42.7%) families one or more diseases were present. Conclusion. From the study results, the following conclusions can be drawn: the most common psychiatric disorders in the immediate and extended family are depression, PTSD, alcoholism and domestic violence, relationships within the family do not affect the incidence of mental disorders among young adults in treatment. Mental disorders among young adults in treatment are more common in families where parents are not in psychiatric treatment than in families in which one or both parents are in psychiatric treatment.